Coastal communities plan for rising water levels (Part 2 of 3)

A cross-section for the year 2100 for raising the West Richmond Dike by building overtop the existing dike. Drawing is from B.C. Ministry of Environment document.

Dealing with the threat of flooding is business as usual for Richmond. River Green, a 2,600-unit residential community on the Richmond waterfront, is being built over the next decade four to six metres above sea level.Handout
/ Vancouver Sun

Driftwood Playground in the park just outside The River District centre. The River District - developed by ParkLane Homes - is a 130-acre community north of the Fraser River between Boundary and Kerr in Vancouver. (photo: undated handout) (for Homes re River District anniversary) [PNG Merlin Archive]
/ Vancouver Sun

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Rising sea levels combined with volatile and intense storms provide a challenge for B.C. coastal municipalities, but it’s a challenge they say they are meeting head on.

Last year, the province set new guidelines for sea dikes and land use in coastal flood-hazard zones as part of the effort to manage an expected sea level rise of 1.2 metres in the next 100 years.

Coastal Cities at Risk, a project studying how to protect people, communities and vital economic sectors that are most at risk from the effects of climate change, is studying Metro Vancouver, which it cites as the Canadian urban area most at risk from rising sea levels and other effects of climate change.

“In an OECD report, (Metro) Vancouver is rated 15th for exposed assets, with $55 billion at risk, and 32nd in terms of population at risk, with 320,000 people exposed,” Cities at Risk said.

Among the infrastructure at risk in Metro, Cities at Risk said, are highways, sewer systems, waste treatment facilities, shipping and ferry terminals, and the international airport. Farmland, residential and industrial areas would be at risk, and about 220,000 people live at or below sea level, protected by 127 kilometres of dikes that were not built to withstand the expected sea level rise due to global warming.

The City of Vancouver adopted the new guidelines last summer, calling for new construction in areas that could be subject to flooding be built up an additional metre, to 4.5 metres above sea level.

“We did that immediately with the West Fraser Lands development River District. They basically raised the entire development one metre without it causing any problems. They built the sidewalks and the streets higher as well,” said Sadhu Johnston, deputy city manager. River District is a new residential development between Kerr Street and Boundary Road south of Marine Drive along the Fraser River.

He said that for infill development, the city works with the developer to creatively meet the new levels without disrupting the streetscape. “We don’t want a streetscape that’s got one building at street level and one a metre higher and it’s kind of all lopsided.”

One option, he said, is to design and install electrical and mechanical equipment — things that might be susceptible to damage during high water levels — so that the building’s ground floor can flood without major disruption, Johnston said.

The city is also doing a coastal risk assessment, which is a detailed assessment of public infrastructure that would be at risk. “That will allow us to take a site-by-site approach instead of a one-size-fits-all approach, so we’re not increasing costs for everyone,” Johnston said.

Johnston said when the city builds new infrastructure, such as replacing the viaducts, they would take projected new ocean levels into account.

“I think the key is, this is long-term work and you need to do it strategically and practically,” Johnston said. “If we’re rebuilding the seawall, of course, let’s raise it a metre. Which is a good example — before we had these guidelines, we rebuilt that seawall and we didn’t increase it a metre and that was a lost opportunity.”

One long-term project that the city is undertaking because of the new challenges with water is separating the sewer system.

“Right now the storm water and the sewer water goes into the same pipe and if you get a massive rainstorm and it overflows, you get combined sewer overflows going into the ocean,” Johnston said. By 2050, the project will be complete. “That will allow us to withstand larger storm events without it causing problems like backups into people’s basements.”

In Richmond, dealing with the threat of flooding is just business as usual. “Richmond has no alternative — they are a major growth centre and they take very strong measures to protect their community against rising sea level and flooding,” said Stephen Sheppard. He is a professor of landscape architecture and forest resources management at the University of British Columbia, and works with Collaborative Advanced Landscape Planning on issues of communities and climate change. “It’s a well-populated city, with more resources than a rural place. They’re like the Netherlands, they don’t have a lot of choice, they have to spend their resources on protection.”

Richmond has a complex system that includes a 3.5-metre-high dike, pumping stations that pump water off Sea Island and a system of ditches.

“The core of our strategy over very, very long term is to basically build the island up. Contrary to some popular misconceptions, Richmond is not below sea level, it is largely at one metre and above the mean tide level. It’s not like New Orleans or anything like that,” said John Irving, director of engineering for Richmond. “If you look at the Fraser Port Lands or the Aspac development around the Olympic oval, those lands have already been built up to four, five, six metres elevation and beyond.”

Irving said if Richmond does have to build up its dike another metre or more, it won’t be a problem. “When you look at the value of the community and the built environment in a place like Richmond, the expenditure required to meet this challenge is really quite low. It’s really a bit of a no-brainer that you can do it,” Irving said, adding that in today’s dollars, the cost to build up the dike would be $200 million to $300 million.

“Our capital program for all utility infrastructure is in the order of $50 million a year and that’s not even stressing us financially,” he said. “Even if this was a sudden emergency and you had to do it, you could probably finish it in a couple of years.”

He said to build something now that is not needed for 100 years is challenging economically. “Most of the infrastructure we build, in terms of water mains and dikes and everything, if you’re lucky you get 100 years’ lifespan out of it, but it might only last 40 or 50 years and then you’re rebuilding it,” Irving said. “So we’re planning for it, but we wouldn’t necessarily run out and try to build up all the dikes another metre today.”

There are not a lot of studies that model what the water level changes will mean in detail for Lower Mainland cities, said Sheppard. He has worked for many years with Delta, and says that community’s next official community plan will include some changes to prepare for sea level rise.

“They are one of the leaders in adaptation; they’ve done a lot of analysis on this ... looking at various flood scenarios,” Sheppard said.

Deborah Harford, executive-director of the Adapt to Climate Change Team at Simon Fraser University, who also works with Cities at Risk studying Vancouver, said municipalities are squeezed for resources because federal and provincial governments download responsibilities onto local governments. “I don’t want to see people lose their homes and all of their possessions ... But we just don’t have billions to chuck at it. The only thing we can do is steel ourselves and plan and implement as soon as we can.”

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Coastal communities plan for rising water levels (Part 2 of 3)

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